Timothy wrote:
The remaining engine seems to be able to do a little more than “take you to the scene of the crash”
Personally, I’ve yet to crash under such a scenario. 
Isn’t the 50/70 rule not good enough as a safety measure? The 50/70 rule is discussed here and states that if you haven’t reached 70% of your takeoff speed by the time you’ve reached 50% of the length of the runway, you should abort your takeoff.
I use this rule sometimes in the bush in Africa to figure out if I will make it off the runway, not specifically if I could still stop, but I would assume that at the halfway point I could still stop on the runway. The 50/70 rule is not perfect, but so are the published performance charts in the POH far from perfect.
Timothy wrote:
In an idle moment, I just checked in the sim that you can do a full aerobatic sequence (rolls, loops, barrel rolls) in a Chieftain OEI.
I do wonder how accurately a sim can replicate this type of stuff – I mean can the programmers really do the science to that degree.
I dont mean that the aircraft will not do it as Bob has so well demonstrated, but is the sim realistic?
I have done both in SEPs (aerobatics) and have always found the sim totally removed from reality, but that might just be the poor quality of the sim I once had.
That rule is about being able to lift off in the remaining runway, and says nothing about whether you can stop. While it is highly likely that you can stop if you abort at that point (only very powerful aircraft accelerate better than they brake), it certainly won’t work if you abort when the engine goes bang a bit later, 3/4 down the runway with 95pc of the lift-off speed.
But in a single, I am not sure worrying about ASDR is of much value. Yes, the engine could fail just before you lift off, and if it does you can stop. But equally likely, it will fail at 10, 20 or 30 feet, and you will end up in the same overshoot. So you do not significantly decrease the risk by not flying unless ASDA > ASDR.
For an aircraft that can climb away on one engine after rotation, having the ASDR reduces the risk to zero.
For the average light twin, there still is a zone after rotation where you will end up in the overshoot if one engine quits (depending on how tall the obstacles are), but it is shorter than in a single and hence the risk reduction is more significant, so worthy of more consideration than in a single.
I’m using X-Plane and Brunner yoke and pedals.
Yes, they are pretty good. Come and have a play if you like.
And re aerobatics – of corse you can! You can do them in a glider, too! Hoover famously did aerobatics in a twin with both engines off and props feathered.
Hoover famously did aerobatics in a twin with both engines off and props feathered.
Yes, but this thread is about asymmetry.
I think I could be convinced to barrel roll a PA31, if I wasn’t so institutionalised. It’s a rather solid beast.
Timothy – thank you that is a very generous offer.
I guess my point was that the sim may replicate the manoeuvre, but do we know that the programme realistically replicates how the “real” aircraft would perform? I am assuming the physics involved in aerobating an asymetric twin is reasonably complex, and then short of the most sophisticated sim (full motion, six degrees of freedon, but even then limited to 150 degrees of visual reference) the sound sight and feel is going to fall short of reality.
In reality simple aerobatic manoeuvres are not complicated especially if positive G are maintained throughout as any aerobat pilot will know and subject to the usual elements not being compromised any aircraft will behave in a predictable way. Having a reasonable idea of the essential parameteres as to what speed and pitch down will be required to complete the manoeuvre and hitting these numbers is probably the most difficult part, especially the first few times!
The flight model is pretty good. I am impressed, for example, by how the aircraft slows down when I magically put fuel in the tanks.
In reality simple aerobatic manoeuvres are not complicated especially if positive G are maintained throughout as any aerobat pilot will know and subject to the usual elements not being compromised any aircraft will behave in a predictable way. Having a reasonable idea of the essential parameteres as to what speed and pitch down will be required to complete the manoeuvre and hitting these numbers is probably the most difficult part, especially the first few times!
My point really wasn’t that a Chieftain could do aerobatics, I knew that and had done it before. My point was for the “an MEP with an engine failure will barely fly” brigade, that I can perform a pretty decent, extended aerobatic sequence with one engine switched off.
